IDL: Remove support for [LogPreviousValue] extended attribute

Source/web/tests/ActivityLoggerTest.cpp

Index: Source/web/tests/ActivityLoggerTest.cpp
diff --git a/Source/web/tests/ActivityLoggerTest.cpp b/Source/web/tests/ActivityLoggerTest.cpp
index 8a21d1c383638527b921fb540ab5edd82740413e..5a0e993a7e9a2ae218532c50e93fa04c9dde43e5 100644
--- a/Source/web/tests/ActivityLoggerTest.cpp
+++ b/Source/web/tests/ActivityLoggerTest.cpp
@@ -36,11 +36,6 @@ public:
         m_loggedActivities.append(apiName + " | " + toCoreStringWithUndefinedOrNullCheck(newValue));
     }
 
-    void logSetter(const String& apiName, const v8::Handle<v8::Value>& newValue, const v8::Handle<v8::Value>& oldValue) OVERRIDE
-    {
-        m_loggedActivities.append(apiName + " | " + toCoreStringWithUndefinedOrNullCheck(oldValue) + " | " + toCoreStringWithUndefinedOrNullCheck(newValue));
-    }
-
     void logMethod(const String& apiName, int argc, const v8::Handle<v8::Value>* argv) OVERRIDE
     {
         String activityString = apiName;